含a-二亚胺配体的Al=Al双键化合物的构筑及反应性研究

Metal-metal bonding is an important and fundamental aspect in chemistry. In recent years, a group of stable compounds containing new metal-metal bonds have been isolated. These species have attracted great interest not only because of the novel bonding nature of the low-valent, low-coordinate metal centers, but also because they display fascinating reactivity toward a variety of small molecules as well as potential applications in catalysis. Aluminum is the most abundant metal in the crust of the Earth and is among the most important ones in the chemical industry. However, it is noticeable that no Al=Al-double bonded compound has been reported so far. Recently, we synthesized the first Al-Al singly bonded compound with an a-diimine ligand. The reactions of the Al-Al-bonded compound with butadienes were conducted in the presence of Na metal, we proposed that the Al-Al single bond compound was first reduced into the double-bonded dialumene. Our computations proved this hypothesis. Based on the above results, we will continue to design and synthesize the new Al=Al-bonded compounds. Further exploration of the reactivity of these compounds toward inorganic and organic small molecules is underway. The electronic structures of the products and the possible reaction mechanisms will be studied by performing DFT computations. This project not only explors the new kind of Metal-Metal bond, but also can provide some important information for promotion its application in various fields.

金属-金属键涉及到新型化学键的本质、成键模式等基本理论问题，是现代化学中重要的研究领域和前沿课题。近几年，一系列新型金属-金属键化合物被报道，且在小分子活化及催化领域表现出奇特的反应性。 Al作为地壳中含量最丰富的金属元素。Al-Al键化学的发展逐渐得到关注。然而由于Al=Al双键化合物至今未分离得到，因此限制了其反应性、催化等领域的研究。合适的配体是稳定金属-金属 (多重) 键的关键因素，我们前期合成了首例以a-二亚胺为配体的Al-Al单键化合物。在考察其反应性过程中，发现Al=Al双键化合物可作为反应中间体参与小分子活化反应，并且理论计算证明此化合物能稳定存在。在本项目中，我们将在以往研究基础上，合成含a-二亚胺配体的Al=Al双键化合物。探索此类化合物对于小分子的反应性，并对反应机理进行研究。此工作不仅可以扩展新型金属-金属键的种类，也对开发此类化合物的应用前景提供有用信息。

金属-金属键涉及到新型化学键的本质、成键模式等基本理论问题，是现代化学中重要研究领域和前沿课题。近几年，一系列金属-金属键化合物被报道，且在小分子活化及催化领域表现出奇特的反应性。主族金属元素在地壳中含量丰富。但其外层电子有限，价态固定，限制了其在催化领域的应用。最近人们利用可变价的配体来弥补金属的不可变价，使化合物既能接受电子又能失去电子，从而具有了过渡金属的性质。另外，合适的配体是稳定金属-金属键的关键因素，我们利用具有氧化还原活性的a-二亚胺为配体，合成低价态低配位数具有多个氧化还原中心的主族金属-金属键化合物。探索此类化合物对于小分子的反应性，通过捕获其他方法难以抓到的有机中间体，对他们的结构进行表征，来了解金属中心的作用方式，进而可以帮助判定反应机理或催化机理，并且目标导向性的催化剂的设计提供理论指导。